Fuji Photo Film Company, Limited

Toshihiro Mandai

Mikio Tomaru

Norio Shibata

Hideaki Takekuma

The coating apparatus and method enable the coating liquid having been scraped-off to be reused without doing any one of the fluid adjusting treatment and the filtering treatment, while maintaining the features of the scraping-off type of extrusion coater, which is suitable for obtaining a uniform and extremely thin coating film. The coating head is provided with two slits: a coating slit and a recovering slit, and the excessive coating liquid having been discharged through the coating slit and applied to the web is scraped-off and recovered through the recovering slit.

Coating method and apparatus

In coating with two slits of a coating slit and a recovering slit, by optimizing the slit clearance of the coating slit and the recovering slit, a coating layer with a very small and even thickness can be obtained. In a coating apparatus in which after a coating liquid is applied to a web to excess through the coating slit, a desired amount of coating liquid is applied to the web by scraping off an excess of coating liquid with a recovering slit, there is provided a slit clearance adjusting device for adjusting the slit clearance of the recovering slit.

Coating apparatus

It is possible to give ultrathin and uniform coating on a flexible web in scraping-off type coating. The distribution of pressure in a web width direction is adjusted by a pressure distribution adjusting device when an excess of coating liquid excessively applied is scraped off by a doctor blade by giving relative pressure to a coating surface of a web and the doctor blade after applying the coating liquid that is more excessive than the desired quantity of the coating liquid on the web by a precoating apparatus while making the web continuously travel.

By optimizing the pressure condition for sucking up an excess of coating liquid with a recovering slit, a coating layer on a web with a very small and even thickness can be obtained. In a coating method using two slits of a coating slit and the recovering slit, a liquid pressure P (MPa) at a suction port of the recovering slit is adjusted in a range of 0.05>P&gE;0. Thus, coating thickness variations in the web width direction of the coating layer formed on the web can be restrained, and score-like coating omission can be prevented from occurring on the coating layer surface.

Coating method

In a case to coat a web by using coating heads which have plural slits, the coating method coats the web by adjusting a running speed, an average high shear viscosity, and a surface tension of the coating liquid of the top layer so that the capillary number Ca, which is calculated by an equation Ca&boxH;U&mgr;/&sgr;, satisfies an inequality 0.1<Ca<4, where U (m/s) is a running speed of the web, &mgr; (Pa&middot;s) is an average high shear viscosity of the coating liquids, and &sgr; (N/m) is a surface tension of the coating liquid for the top layer.

Method for coating a running web using a plurality of coating liquids

Thickness unevenness of a coating liquid layer in a width direction of a web is adjusted by moving a guide roller at the proximity of a coating rod so as to deliberately provide tension variation in the width direction of the web in purpose of forming the coating liquid layer with a desired thickness on the web by the coating rod.

Method for coating a running web using a coated rod

Method for coating a running web using a coating rod

Edge faces with level differences are formed by assembling blocks constructing a coating head, and level difference variances in the width direction of a web are measured by a level difference variance measurement device. Then, the level difference variances are adjusted with reference to measured results, so that the level difference variances can be reduced. Therefore, coating layers can be uniformly formed on the web.

Extrusion-type coating method and apparatus

In a case to coat a web by using coating heads which have plural slits, the coating method coats the web by adjusting a running speed, an average high shear viscosity, and a surface tension of the coating liquid of the top layer so that the capillary number Ca, which is calculated by an equation Ca&equals;U&mgr;/&sgr;, satisfies an inequality 0.1<Ca<4, where U (m/s) is a running speed of the web, &mgr; (Pa&middot;s) is an average high shear viscosity of the coating liquids, and &sgr; (N/m) is a surface tension of the coating liquid for the top layer.

An extrusion coating head comprises an upstream side block ( ) and a downstream side block ( ) aligned in the conveying direction, and adjusting mechanism. The upstream and downstream side blocks ( ) respectively have edge surfaces ( ) on which the flexible support ( ) is pressed. The upstream and downstream side blocks ( ) define therebetween a slit ( ) through which a coating composition can be extruded and applied onto the flexible support. The adjusting mechanism adjusts a length (t) of a perpendicular line which is drawn from an upstream end (A) of the edge surface of the downstream side block to a tangential line (L) of the edge surface of the downstream side block which is drawn from a downstream end of the edge surface of the upstream side block, to thereby adjust a distribution of a coating thickness on the flexible support in the width direction.

Extrusion coating head and coating method for flexible support

A method and apparatus for removing dust from a base film effectively so that electrostatic charges of the base film are reduced while the cleaning effect is kept high. After a cleaning solvent is applied onto one surface of a base film by a precoater, a rod member is pressed against the base film while the cleaning solvent remains on the base film, so that deposits on the base film are separated and scraped together with the cleaning solvent from the base film by the rod member. Just after the deposits are scraped from the base member, a solvent, of the same kind as the cleaning solvent or a mixture of a solvent of the same kind as the cleaning solvent and an additive mixed thereto, is applied onto the base film while the surface of the base film coated with the cleaning solvent is not exposed to an atmospheric air space.

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Odawara, Japan

Toshihiro Mandai